Angular speed detection device
The purpose of the present invention is to provide an inertial force detection device that can more accurately detect faults in a temperature sensor. Provided is an inertial force detection device configured so that in a state where an oscillating body is made to oscillate in a first direction, the amount of displacement when the oscillating body is displaced in a second direction due to the generation of angular velocity is detected as angular velocity, wherein the inertial force detection device has a means for performing control so that the oscillating body enters a state of resonance in the first direction, a temperature detection means for detecting temperature, and a means for detecting faults in the temperature detection means, and outputs a plurality of signals, which indicate the fault detection results of the three means, continuously from a single signal wire.
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The present invention relates to an inertial force detecting apparatus for detection inertial force acting at the time of automobile travel.
BACKGROUND ARTAn exemplary inertial force detection apparatus is an angular velocity sensor that is used as an anti-skid control device to ensure safety at automobile travel in order to detect angular velocity attributed to skids or turnings on compacted snow roads or frozen roads. In order to enhance angular velocity detection accuracy, a temperature characteristic output by a sensor is corrected, in some cases, by using a temperature sensor. Unfortunately, however, when the temperature sensor has a failure, erroneous correction might be performed at temperature characteristic correction. This erroneous correction would lead to the output of a value from the angular velocity sensor, that is different from the original output value. In order to prevent this, detection of a failure in the temperature sensor is needed, and techniques as described in PTL 1 and 2 are disclosed as methods for detecting a failure in the temperature sensor attached to the angular velocity sensor. PTL 1 describes an exemplary case where a sensor failure is determined by comparing a change amount of resonant frequency from a reference value with a change amount of the temperature sensor output from a reference value. PTL 2 describes an exemplary case where temperature sensors are provided on an angular velocity detection element and on a control unit, and the sensor outputs are compared with each other to determine a temperature sensor failure.
CITATION LIST Patent Literatures
- PTL 1: JP 2009-508130 A
- PTL 2: JP 2000-105125 A
Nevertheless, in order to ensure normality of operation of each of these failure detection functions, it would be necessary to provide a function of detecting a failure in the failure detection function itself, in addition to the above-described techniques.
The present invention is intended to provide an inertial force detection apparatus capable of detecting a failure in a temperature sensor with higher accuracy.
Solution to ProblemAn inertial force detection apparatus configured to detect a displacement amount when an oscillating body oscillating in a first direction is displaced in a second direction due to generation of angular velocity, as an angular velocity, includes a unit configured to control the oscillating body to be in a resonant state in the first direction, a temperature detection unit configured to detect temperature, and a unit configured to detect a failure in the temperature detection unit. The inertial force detection apparatus sequentially outputs a plurality of signals indicating failure detection results of the three units, from one signal line.
Advantageous Effects of InventionIt is possible to provide an inertial force detection apparatus capable of detecting failures in a temperature sensor with higher accuracy.
Hereinafter, exemplary embodiments of the present invention will be described with reference to
Also provided are a capacitance detector 110, an AD converter 145, a synchronous detector 131, and an oscillation frequency adjustment unit 151. The capacitance detector 110 detects displacement acting on the detection element 101 in the oscillation axis direction by detecting a difference between the capacitance across the detection element 101 and the fixed electrode 104, and the capacitance across the detection element 101 and the fixed electrode 105. The AD converter 145 converts output of the capacitance detector 110 into a digital signal. The synchronous detector 131 is formed with a multiplier 113 that performs synchronous detection with a detection signal ø1. The oscillation frequency adjustment unit 151 is formed with an integrator 118 that adds output of the synchronous detector 131 for every fixed cycle.
Also provided are a capacitance detector 112, an AD converter 146, a multiplier 115, and an angular velocity detection unit 153. The capacitance detector 112 detects displacement acting on the oscillator 102 by the Coriolis force by detecting a difference between the capacitance across the oscillator 102 and the fixed electrode 106, and the capacitance across the oscillator 102 and the fixed electrode 107, and converts the displacement into a digital signal. The AD converter 146 converts output from the capacitance detector 112 into a digital signal. The multiplier 115 is provided for performing synchronous detection with the detection signal col. The angular velocity detection unit 153 is formed with an integrator 120 that adds output of the multiplier 115 for every fixed cycle.
Also provided are a voltage controlled oscillator (VCO) 122 and a clock generator 123. The VCO 122 outputs a basic clock of a frequency in accordance with the output of the integrator 118. The clock generator 123 performs frequency-division of the output of the VCO 122 and outputs a drive signal and the detection signal col.
Also provided is a characteristic correction 139 configured to correct the output of the angular velocity sensor in accordance with the output of the temperature sensor 137.
Also provided is a temperature sensor failure detection unit 161. The temperature sensor failure detection unit 161 includes a half-cycle integration 162, a resonance determination value register 163, a temperature determination value generator 164, a switch 165, a switch 166, and a comparison unit 167. The half-cycle integration 162 performs integration of synchronous detection output for ½ cycle with the synchronous detector 131. The resonance determination value register 163 is provided for detecting, from output of the synchronous detector 131, that the angular velocity detection element 101 is oscillating at the resonant frequency. The temperature determination value generator 164 is provided to detect a failure in the temperature sensor 137. The switch 165 performs changeover between failure detection target signals. The switch 166 performs changeover between failure determination values. The comparison unit 167 determines a failure by comparing the failure detection target signal with the determination value.
The configuration also includes a communication unit 143 configured to output angular velocity detection results from the angular velocity characteristic correction unit 139 and failure detection results from the temperature sensor failure detection unit 161, to an external device.
Next, operation will be described.
For the above-described reasons, the oscillation frequency adjustment unit 151 automatically adjusts the frequency of the drive signal all the time such that the oscillation of the oscillator 102 in the oscillation axis direction is in the resonance state. Displacement of the angular velocity detection element 101 by the drive signal is detected by the fixed electrodes 104 and 105 and is input into the capacitance detector 110. Oscillation displacement in the oscillation axis direction is detected by performing synchronous detection at the synchronous detector 131 onto the oscillator displacement signal obtained via the capacitance detector 110 and the AD converter 145. Next, the signal obtained at the synchronous detector 131 is integrated on the integrator 118.
Next, in order to determine a value set on a drive amplitude register 125 as amplitude, multiplication with the output of the clock generator 123 is performed at the multiplier 124 to generate a drive signal.
101 angular velocity detection element
102 oscillator
103, 104, 105, 106, 107 fixed electrode
110, 112 capacitance detector
113, 115, 124 multiplier
118, 120 integrator
122 voltage control oscillator
123 clock generator
125 drive amplitude register
137 temperature sensor
138, 145, 146 AD converter
139 angular velocity characteristic correction unit
143 communication unit
147 DA converter
151 oscillation frequency adjustment unit
153 angular velocity detection unit
154 servo signal generator
161 temperature sensor failure detection unit
162 one-cycle integrator
163 resonance determination value register
164 temperature determination value generator
165, 166 changeover switch
167 comparison unit
Claims
1. An inertial force detection apparatus configured to detect a displacement amount when an oscillating body oscillating in a first direction is displaced in a second direction due to generation of angular velocity, as an angular velocity, the inertial force detection apparatus comprising:
- a unit configured to control such that the oscillating body comes into a resonance state in the first direction;
- a temperature detection unit configured to detect temperature; and
- a unit configured to detect a failure in the temperature detection unit,
- wherein a plurality of signals indicating failure detection results of the three units is sequentially output from one signal line.
2. The inertial force detection apparatus according to claim 1,
- wherein a failure in the temperature detection unit is detected on the basis of a signal supplied to cause the oscillating body to oscillate in the first direction, a signal attributed to displacement of the oscillating body, generated by the oscillation in the first direction, and a signal output by the temperature detection unit.
3. The inertial force detection apparatus according to claim 1,
- wherein the unit configured to detect a failure in the temperature detection unit includes a unit that generates a failure determination threshold that changes in accordance with the temperature, a threshold comparison unit that compares output of the temperature detection unit with the failure determination threshold, determines that the result is normal when the output is in a failure determination threshold range, and determines that the result is a failure when the output is out of the range, and
- the signal generated in a unit configured to detect a failure in the unit that generates a failure determination threshold and the signal generated in a unit configured to detect a failure in the threshold comparison unit, are output as a failure detection result of the unit configured to detect a failure in the temperature detection unit.
4. The inertial force detection apparatus according to claim 1,
- wherein determination of a change from a non-resonance state to a resonance state, of the oscillating body, is performed before failure detection of the temperature detection unit is performed.
5. The inertial force detection apparatus according to claim 1,
- wherein the plurality of sequential signals corresponds to a signal indicating whether the oscillating body is in a resonance state and to a signal indicating a failure detection result of the temperature detection unit.
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Type: Grant
Filed: Apr 8, 2015
Date of Patent: Apr 10, 2018
Patent Publication Number: 20170045360
Assignee: Hitachi Automotive Systems, Ltd. (Ibaraki)
Inventors: Toshiaki Nakamura (Tokyo), Heewon Jeong (Hitachinaka), Masahide Hayashi (Hitachinaka)
Primary Examiner: Jewel V Dowtin
Application Number: 15/304,640
International Classification: G01C 19/5726 (20120101); H01L 29/84 (20060101);